Most failed bathrooms in Glasgow do not fail because of taste. They fail because water finds its way somewhere it should not. By the time you can see the problem, the damage is usually in the structure behind the tile. The single biggest reason this happens is poor waterproofing.
This guide sits underneath our complete guide to bathroom fitting in Glasgow and our service page on tiling and waterproofing.
What tanking actually is
Tanking is the application of a continuous waterproof membrane to walls and floor in wet areas of a bathroom, before any tile goes on top. It is not the tile. It is not the grout. It is not the silicone. Tile, grout and silicone are water resistant, not waterproof, and they all rely on the membrane underneath them to keep the structure dry.
A tanking system usually consists of a primer, a liquid or sheet membrane, and reinforcement tape or fabric at all junctions, internal corners and pipe penetrations. Applied as a system from one manufacturer, it forms a sealed envelope around the wet zone.
Where it must go
- Full bathroom wet rooms: floor and walls in the entire shower area, plus turn ups onto adjacent walls.
- Walk-in showers: floor of the shower zone plus walls to a minimum height of 1.8 to 2 metres around the shower head.
- Behind baths with showers over them: the splash zone, taken behind the bath surround and onto the floor.
- Around all pipe penetrations: reinforcement tape and detail bands so water cannot track behind the pipe.
In our experience the most common failure point in Glasgow tenement bathrooms is the floor to wall junction in the shower zone. It is exactly where reinforcement tape was either skipped or under-lapped.
Substrates and why they matter
A tanking system is only as good as what it is bonded to. The substrate decisions usually look like this.
- Timber floors: almost always need overboarding with cement-based backer board, screwed and primed, before tanking.
- Concrete floors: usually need priming and any cracks filled. Sometimes a self-levelling compound is needed.
- Lath and plaster walls: common in older Glasgow homes. Almost always need to be removed and replaced with plasterboard plus backer board where tile will live.
- Plasterboard walls: moisture resistant board is the minimum behind tile. Standard plasterboard is not.
Floor falls in wet rooms
In a wet room, the floor has to actively guide water toward the drain. That means building the floor up with falls on all sides of the drain, usually with a pre-formed former or a sand and cement screed laid to falls. Done properly, water flows away within seconds. Done badly, you get puddles that sit at the door.
For more on wet room construction, see our pages on wet rooms and the comparison wet room or walk-in shower, which is right for you.
Grout, silicone and movement joints
Tile, grout and silicone are the visible layer of a waterproof bathroom. They will not save a bad membrane, but they finish the job properly.
- Grout belongs in tile joints. It is rigid and will crack if used at a corner where movement happens.
- Silicone belongs at every internal corner, at all tile-to-bath or tile-to-tray junctions, and at every pipe penetration.
- Movement joints are not optional. Without them, the natural movement of the building cracks grout within a year.
How to spot it being done properly
You do not need to be a tiler to spot good tanking work. Watch for these signs.
- The fitter uses a named system, primer included, not a tub of pink paint and a brush.
- Reinforcement tape is applied at every internal corner, floor-to-wall junction and pipe penetration.
- Drying times between coats are respected. Tanking is not rushed onto the wall and tiled the same afternoon.
- A water test is carried out on a wet room floor before the tiles go on.
- The fitter is willing to explain what they are doing and why.
What a bad job looks like later
A poorly waterproofed Glasgow bathroom usually shows itself within twelve months. Symptoms include blown grout in the shower area, mould behind silicone that returns no matter how often you clean it, a soft floor at the shower door, or a damp patch on the ceiling of the flat below. None of these are tile problems. They are membrane problems.
Get matched with someone who does this properly
Stonewater Bathrooms specifically vets fitters on waterproofing work. We connect homeowners with tradespeople who treat tanking as the most important stage of the job, not the boring one. When you submit your details, we will match you with a fitter who covers your area and who has been checked on this work.